Blood pump



Feb. 13, 1962 A. THoMAs 3,020,846

BLOOD PUMP Filed Jan. 30. 1959 3 Sheets-Sheet 1 Feb. 13, 1962 A, THOMAS 3,020,846

BLOOD PUMP Filed Jan. 30, 1959 3 Sheea'cs-Sheei'l 2 XII *V 145 YET A6] l5 l f- M44 l .146/ 745 5l7 /59 58 140\ C'JC.' n T' 141 V46.2165, T 460 13a 4 nv www@ fr A//ef" 7270/7/15 .ATTORNEY Feb. 13, 1962 A, THOMAS 3,020,846

, BLOOD PUMP Filed Jan. 50. 1959 3 Sheets-Sheet 3 @WMZ A TTNFY nite This invention concerns pumps which may be used for industrial purposes and which are particularly adapted for medical use for the circulation of blood.

The invention concerns pumps of the type comprising a flexible tube of resilient material which is rhythmically compressed so as to expel liquid contained in the tube at the region of compression and wherein, upon release of the pressure, the tube assumes its original shape, due to its resilience, and draws in a further quantity of liquid ready for the next delivery stroke.

Hitherto a pump of the type referred to has been arranged so that the flexible tube is compressed either by the pressure exerted on its outer surface by a gas or a liquid or by mechanical action due to levers or by a roller carried by the levers. In other cases the levers have been so arranged at spaced intervals along a shaft as to compress the ilexible tube one after the other.

If the compression forces are suitably spaced the delivery from the pump may be intermittent without there being any question, for example, of physiological pulsations. lf the phases of compression take place at short intervals it may be arranged that the pulses imparted to the liquid delivered from the pump succeed one another so that eiectively the delivery from the pump is substantially continuous. In such an arrangement it is not necessary to provide valves for controlling the admission and discharge of the liquid from the exible tube Since each compression phase of the ilexible tube is equivalent to a valve actuation. This occurs, for example, with pumps having rollers or a series of iingers or levers which are successively engaged with the flexible tube. Such arrangements are used for the circulation of liquids, more especially for the artificial circulation of the blood. The pumps produce a ilow of liquid in accordance with an undulatory curve, the undulations of which, however, are of small amplitude so that the How can be substantially continuous and not physiologically pulsatory.

The present invention has for its object to provide an improved construction of pump of the type set forth which is particularly suitable for the circulation of blood in the apparatus described in the specification of U.S. Serial No. 789,364.

Constructions of pump according to the present invention will now be described, by way of example only, with reference to the accompanying drawings whereof:

FIG. 1 is a diagrammatic sectional elevation of a pump according to the present invention;

FIGS. 2 and 3 are respectively sections on the lines II-II and III-III of FIG. l;

FIG. 4 is a section on the line IV-IV of FIG. 3;

FIG. 5 is a plan View of a valve member which constitutes a part of the pump of FIG. 1;

FIG. 6 is aV longitudinal diagrammatic section of a lter for use with the pump of FIG. l;

FIG. 7 is a diagrammatic view of a mechanism for compressing the flexible tubes which constitute a part of the pump of FIG. 1;

FIG. 8 is a View in the direction of the arrow VIII of FIG. 7;

FIG. 9 is a view corresponding to FIG. 8 showing an alternative construction;

FIG. 10 is a section on the line X-X of FIG. 9;

icc

FIGS. 11 and 12 are sections on the lines Xl--XI and XII-XII of FIG. 7;

FIG. 13 is a diagrammatic view showing a modied construction of the mechanism shown in FIG. 7;

FIG. 14 is a sectional elevation of yet a further alternative construction of mechanism for compressing the flexible tubes, the mechanism being shown adjusted for minimum delivery, and

FIG. 15 is a view similar to FIG. 14 showing the mechanism thereof adjusted for maximum delivery.

Referring to the drawings: the pump assembly according to this invention comprises two main parts--on the one hand a pulsatory pump and on the other hand an electromechanical apparatus for actuating and controlling the pump assembly.

The pulsatory pump assembly comprises two flexible tubes of resilient material, two suction valves, two delivery valves and a single inlet to the pump and an outlet therefrom.

The flexible tubes 101 (FIGS. l, 7 and 13) are of rub ber or other natural or synthetic material of the required resilience. Their length and their internal and external diameters are selected to accord with the ow rate for the liquid which is to be produced while the wall thickness and the quality of the material are selected to provide a high degree of resilience with ready deformation. The two tubes are connected in parallel and, as lshowin in FIG. l, are arranged vertically side-by-side. At the lower end of each tube 101 there is a suction valve 102 and at the upper end of each tube there is a discharge valve 103i. The suction and discharge valves may take several constructional forms and may be made of metal, rubber or plastic material.

Each valve 102 comprises a small chamber having circularV lateral walls 104 (FIGS. 2 and 3) with upper and lower walls 10S and 106 respectively which are sub stantially parallel.

The upper and lower walls 10S and 106 respectively. are each formed with an opening. Thus, each suction Valve 102 has an inlet opening 107 in its lower wall 106 and an outlet opening 103 in its upper wall 105. The opening 108 communicates with a iiange 109 which is received within the lower end of a tube 101. v v

' Each of the discharge valves 103 is similarly constructed: the valve has an inlet opening 110 in its lower wall 106', the opening 110 communicating with a flange 109' which enters the upper end of a tube 101, and an outlet opening 111 in the upper wall 105 of the valve. The tubes 101 are secured to the anges 109 by bands 112.

Each of the valves 102 and 103 has a flexible disc 113, 113 respectively of rubber or plastic material within a cavity between its upper and lower walls. The inner face of the lower wall 106, 106 of each valve is ilat and constitutes a valve seat. The disc 113 when applied to the valve seat of the suction valve 102 will close the opening 107. In relation to each discharge valve 103 disc 113 will close the opening 110. Y

The peripheral edges of the Vdiscs 113, 113 are scalloped or similarly formed to enable the blood passing through the valve to do so more readily, the size of the scallops being so selected, however, that the valve discs can completely close the openings 107 and 110 in duidtight manner.

The suction valve (see FIG. 2) also comprises a pair of inwardly directed lugs 114 arranged on opposite sides of the disc 113, the lugs being integral with the inner face of the wall 105. The lugs 114 ensure that when a disc 1.13 is against an upper wall `blood readily travels around the scalloped edge of the disc 13 and is discharged through the opening 108 and the ilange 109 into the tube 101. When the disc 113 is against lugs 114 blood is readily drawn through the opening y107 past the suction 3 valves and into the tube 101. Conversely, when a disc 113 is in engagement with the wall 106, which is not provided with lugs correspondingy to the lugs 114, the disc 113 will effectively close the openings 107 so that liquid Within tube 101 cannot fiow back and 'oe discharged through the opening 107.

The discharge valves 103 are similarly provided with lugs 114 on the inner face of the upper wall with the consequence that when the disc 113 bears upon the inner face of the lower wall 106 the opening 110 is closed but when the disc 113 is applied against the upper wall 105 it engages with the lugs 114 with the consequence that blood can pass around the disc 113 for discharge through the opening 111.

The extent of movement of the discs 113, 113 of the suction and discharge valves is limited on the one hand by a pair of bars 115, 115 which are located beneath the discs, and on the other hand by a bar 116, 116 which is above the discs and at the level of the opening 108, for the suction valves, and of the opening 111, for the discharge valves. These bars prevent the discs 113, 113 from being forced through the valve openings when the liquid enters and leaves the tubes 101.

The bars 116, 116 permit upward movement of the discs 115, 115 to be so restricted that blood passes the valve mainly as a consequence of the deformation of the scalloped edge thereof so that when the valves are closed (upon engagement of the discs 113, 113 with the lower walls 106, 106') the time occupied in closing the valves is relatively small whereby back flow of liquid through the valves is reduced to a minimum.

The cavities within which the discs 113, 113 lie are each provided with a side opening 117, 117' which is closed by a plate 118, 118 secured in position by studs 119, 119', a fiexible packing piece 120, 120' being provided between the plate 11S, 118 and the valve casing. Removal of the plate 11S, 11S gives access to the disc 113, 113 for removal and replacement.

The openings 107 are connected by a Y-shaped duct 121 which communicates with a common suction orifice 122. Similarly the openings 111 communicate with a Y-shaped duct 121 which communicates with a cornmon discharge orifice 123.

The arrangement described comprising the pair of tubes 101 and the associated suction and discharge valves together with the inlet and outlet orifices leading thereto constitute a pump assembly for delivery of blood from duct 23 of the apparatus of FIG. 1 through the orifice 122 to the orifice 123 by alternate compression and release of the tubes 101 it being understood that upon release of compression of each of the tubes their natural resilience results in their expansion to their original shape during which function blood is drawn into the tubes from the orifice 122 past the suction valves 102 which are then open, the discharge valves 103 being then closed. While this is occurring in one of the tubesv the other, which has previously been filled with liquid, is compressed so that the liquid is delivered past the discharge valve 103 and out through the orifice 123, the suction valve remaining closed during this operation. It follows that each time one of the tubes 101 is compressed blood is discharged through the orifice 123. The pump functions in a pulsatory manner and the nature of the pulsations depends upon the frequency with which the tubes are compressed and the degree of compression of each sleeve in relation to their frequency and volume.

The blood delivered from the orifice 123 can be filtered (before returning to the body) by a detachable filter 124 (FlG. 6). The filter 124 comprises a cylindrical duct 125 having an intake opening 126 and a support member 129 having a discharge opening 130, the member 129 being secured to the duct 125 by a flange 132 which is clamped by bolts 136 to a ange 127 of the duct 125, a resilient packing 135 being provided between the flanges. The member 129 has an inward extension 131 which supports a cage comprising rods 133, for example eight in number, which are joined together at their ends remote from the member 129. A filtering membrane, for example of polyamide fabric in the form of a cylindrical bag, is mounted upon the cage 133 and the neck of the bag is clamped to the extension 131 by an encircling band 134a. The filtering bag is readily mounted upon the cage upon removal of the support member 129 from the duct by releasing the bolts 136. The liquid from the orifice 123 is delivered to the opening 126 and, having passed through the filter bag 134, is discharged at 130.

Referring now to FIGS. 7 and 8: the pump assembly shown in FIG. 1 is actuated and controlled by an electromechanical mechanism Which will now be described, the mechanism being provided for alternately squeezing the tubes 101.

The electro-mechanical assembly comprises an electric motor (not shown) and a speed reduction gearing driven thereby, the reduction gearing or the motor or both being controlled so as to vary the speed. The motor-reduction gear assembly is coupled to a shaft 137 which is driven by the motor at a selected speed. A crank disc 138 is secured by screws 139 to the shaft 137 so that the crank disc is driven by the motor. The crank disc has a diametral slot 140 within which a bar 141 slides, the bar 141 having a slot 142 through which passes a stud 143 which carries a nut 144, the arrangement being that when the nut 144 is drawn up, the bar 141 is clamped to the crank 138 in any appropriate position along groove 140. The bar 141 carries a crank pin 145 upon which one end of a connecting rod 156 is mounted. The connecting rod 156 is adjustable as to length by varying the position of the threaded rod 15S in the sleeve 157, a lock nut 139 holding the parts against inadvertent movement. An unthreaded portion 160 of the connecting rod 156 passes through a ring 161 (FIG. 1l) which is pivotally mounted to an arm 164 of the screws 165, the part 160 being secured to the ring 161 by a shoulder 162 and by a knurled nut 163 which is threaded upon the end of the connecting rod 156.

The arm 164 has a spigot 166 which enters a rectangu lar section shaft 167 mounted upon a shaft 168 and secured thereto by a grab screw 169. The spigot 166 permits relative movement of the arm 164 and the shaft 167. Any other known or convenient joint permitting corresponding relative movements may be used in place of the spigot connection.

Also mounted upon the shaft 168 are a pair of blades 170 which are formed with rings 171 through which passes the shaft 168.

The shaft 167 is extended downwardly from the shaft 168 so that it lies between the pair of blades 170. The extension of the shaft 167 has a recess 172 within which is mounted a lead screw 173 having a bearing support, at 174, with the shaft 167. The lead screw 173 carries an abutment 175 within the recess 172 and a hand wheel 176 outside the recess. Mounted on the lead screw 173 is a cross piece 177 the ends of which carry rollers 173 to engage with the inner faces of the blades 170. By adjusting the le-ad screws 173 the cross piece 177 is moved lengthwise of the shaft 167 and the distance between the blades 170 is thereby adjusted.

With rotation of the crank disc 138 the connecting f rod 156 is moved backwards and forwards thereby to adjust the arm 164 and the shaft 167. The latter, through the cross piece 17'/ and the rollers 178 will oscillate the blades 170 towards and away from fixed abutments 179. It is arranged that each of the tubes 101 is disposed between the space separating one of the blades 170 from the co-operating abutments 179, as is shown in FIG. 7. Consequently as the blades 170 are oscillating one of the tubes will be compressed (that is the tube which is engaged by the blade 170 which is moving towards the abutment 179) while the other tube will be relieved of compression. Thus, the mechanism of FIG. 7 is utilized alternately to compress the tubes 101 whereby the pump assembly is actuated.

With adjustment of the lead screw 173 the blades 178 are moved relatively to the abutment 179 so that each tube 161 is compressed to a greater or lesser extent with each oscillation of the shaft 167.

Referring now to FIGS. 9 and 10: the crank disc 138 has a diametral recess 147 along which a screwed rod 148 extends, the screwed rod having an unthreaded portion 149 which is supported in the bearing 151 formed in the crank disc. Similarly the end 153 of the rod 148 is supported in another bearing 151. The part 153 carries a band 154 while the part 149 carries a hand wheel 150.

A block 155 is mouned on the screw threaded rod 148 and carries the crank pin 145. With adjustment of the hand wheel 150 the throw of the crank pin 145 is varied. A wing nut 52 is provided to lock the threaded rod 140 against inadvertent rotation after the crank pin 145 has been set to a required position.

Instead of the mechanism shown in FIG. 7 it may be arranged (as shown in FIG. 13) that the blades 170 are carried by the shaft 167 so as to lie outside the pair of tubes 101. A central fixed abutment 180 is provided between the tubes. As the shaft 167 oscillates the blades 178 are moved towards, and away from, the abutment 188 whereby the tubes are alternatively compressed and relieved of compression. The plate 188 may comprise two arms which are adjustable relatively to the blades 170 so that the extent of compression of the tubes 101 is variable as described above.

Referring now to FIGS. 14 and 15: the tubes 101 are located between a pair of blades 170 and a central plate 180 is located between the tubes 101. The central plate 188 is secured against movement (as at 181) to the main frame of the mechanismpart of the frame is shown at 182. In the particular arrangement described the main frame 182 also carries a threaded spindle 183 upon which is mounted a knurled nut 184. The threaded spindle 183 passes through the fork arms of the frame 1.82. With rotation of the knurled nut 184 the spindle 183 is adjusted axially thereby angularly to adjust the central plate 188 about the pivot 181. This has the eiect of varying the extent of the compression of the tubes 1.

The blades 170 are carried by a cross head 185 which receives the limb 186 of a T-shaped member of which the other limb 187 passes through a ball joint 188. The ball joint 188 is received by a carrier 189 which is mounted in a tubular shaft 190 so that the ball joint is eccentric with respect to the axis of rotation of the shaft 190. The shaft 190 is driven in any suitable manner (not shown) through pins 191 (or axial splines) which permit the drive to shaft 198 to be maintained while it is moved axially.

-As the shaft 190 is rotated a conic movement is imparted to the limb 187 by the eccentrically mounted ball joint 188 with the result that the limb 186 performs an oscillatory movement about the axis 192. Consequently the blades 170 are moved towards and away from the central plate 180 thereby alternately to compress and relieve the tubes 101 from compression.

The hollow shaft 190 is mounted on bearings 193 within a housing 194 which is slidable axially within the frame 195. The housing 194 is screw threaded at 198 into the main frame 195 and carries a skew gear 196 which is engaged by a skew pinion 197. When the pinion 197 is rotated the housing 194 is adjusted axially relatively to the housing 195 and the position of the ball joint 188 lengthwise of the limb 187 is varied. When the ball joint is near the free end of the limb 187 the extent of oscillation of the blades 170 is relatively small. This is shown in FIG. 14. When, however, the ball joint 188 is moved nearer the limb 186 (as shown in FIG. 15) the extent of the oscillation of the blades 170 is increased.

j 6 In this way the pump delivery may be adjusted during operation.

The plate in the arrangement illustrated in FIGS. 14 and 15 is normally stationary. However, according to an alternative arrangement the plate 180 may oscillate towards and away from the blades 170, while the latter also oscillate, so that the frequency of compression is suitably varied.

The motor for driving the hollow shaft in the construction o-f FIGS. 14 and l5 or for driving the shaft 137 in the constructions of FIGS. 7 and 8 may be automatically controlled so as to ensure a constant pump delivery. Thus, for example, the delivery from the pump may pass to a well so that variations of the depth of the liquid in the well adjust a oat to actuate an electric micro-switch. The micro-switch regulates a suitable electronic device to adjust the pump output through a servoadevice which may incorporate a follow-up mechanism to ensure that hunting is reduced or eliminated.

What is claimed is:

l. A pumping mechanism for circulating a liquid with a pulsating action comprising two resilient tubes arranged in parallel, a suction valve and a discharge valve for each tube, both suction valves being at the same ends of the tubes and both discharge valves being at the other ends of the tubes, a common huid inlet leading to both suction valves, a common fluid outlet leading from the discharge valves, each of said valves comprising a housing forming a valve chamber having upper land lower walls with outlet and inlet openings respectively, a ilexible valve disc having a scalloped peripheral edge disposed in said housing, said lower wall having a seat to receive said valve disc for closing said inlet opening and a stop member positioned to limit the movement of the central portion of said disc for preventing said disc from seating against said upper wall to close said outlet openings whereby liquid iows around said scalloped peripheral edge of said disc to said outlet openings, and means for alternately subjecting the tubes to a predetermined compression over substantially the entire length of each tube.

2. A mechanism according to claim l in which the discs are within a body having a lateral opening and there is provided a closure plate for the opening, access being obtained to the discs through said opening on removal of the plate.

3. A mechanism as claimed in claim l wherein the means for alternately compressing the tubes comprises for each tube a fixed abutment and a blade disposed on the opposite side of said tube, said blade being mounted for reciprocation in a direction to compress the tube against said abutment.

4. A mechanism as claimed in claim 3 wherein the blades are mounted on opposite Sides of the respective tubes and are coupled together for reciprocation in unison simultaneously compressing one tube and releasing the other tube from compression.

5. A mechanism as set forth in claim 4 wherein said blades are coupled for adjustment of their relative spacing for thereby varying the extent of compression of said tubes.

6. A mechanism as set forth in claim 4 wherein a crank mechanism is connected to reciprocate said blades, said crank mechanism including means for varying the amplitude of reciprocation of said blades.

7. A pumping mechanism for circulating a liquid with a pulsating action comprising two resilient tubes arranged in parallel, a suction valve and a discharge valve for each tube, both suction valves being at the same ends of the tubes and both discharge valves being at the other ends of the tubes, a common uid inlet leading to both section valves, a common iluid outlet leading from the discharge valves, means for alternately subjecting the tubes to a predetermined compression over substantially the entire length of each tube, said last means comprising for each tube a xed abutment and a blade disposed on opposite a sides of said tube, said blade being mounted for recprocation in a direction to compress the tube against said abutment, said blades being mounted on opposite sides of the respective tubes and being coupled together for reciproeation in unison for simultaneously compressing one tube and releasing the other tube from compression.

8. A pumping mechanism for circulating a liquid with a pulsating action comprising two resilient tubes arranged in parallel, a suction valve and a discharge valve for each tube, both suction valves being at the same ends of the tubes and both discharge valves being at the other ends of the tubes, a common fluid inlet leading to both suction valves, a common uid outlet leading from the discharge valves, and means for alternately subjecting said tubes to a predetermined compression over substantially the entire length of each tube, said means comprising a fixed abutment for each tube and a blade disposed on the opposite side of said tube, said blade being mounted for reciprocation in a direction to compress the tube against said abutment.

9. A mechanism as set forth in claim 7 wherein said blades are coupled for adjustment of their relative spac- References Cited in the file of this patent UNITED STATES PATENTS 1,282,145 Tobler Oct. 22, 1918 1,627,680 Vollmann May 10, 1927 2,713,858 Armstrong et al. July 26, 1955 FOREIGN PATENTS 131,864 Germany July 3, 1902 542,678 Italy Apr. 30, 1956 OTHER REFERENCES Mustard et al.: Extracorporal Circulation, Surgery, vol. 32, No. 5, pp. 803-810 (pp. 803-04 relied on), November 1952. 

